Green-fluorescent proteins (GFPs) have been found to be useful tools for genetically labeling proteins, enzymes, antibodies, cells, tissues, organs, and organisms. In addition, GFP is widely used as a brilliant and sensitive reporter in biochemical assays. GFP's desirability comes from its intrinsic fluorescence and the fact that GFP can be introduced genetically. GFP makes its own intrinsic chromophore (fluorophore) without any required enzymes or cofactors other than molecular oxygen. (Prasher DC, Eckenrode VK, Ward WW, Prendergast FG, Cormier MJ. Primary structure of the Aequorea victoria green-fluorescent protein. Gene. 1992 Feb. 15;111(2):229-33; Chalfie M, Tu Y, Euskirchen G, Ward W W, Prasher D C. Green fluorescent protein as a marker for gene expression. Science. 1994 Feb. 11;263(5148):802-5.)
The known GFPs have mostly originated from members of the phylum Cnidaria (which includes jellyfish, sea pansies, corals, sea pens, and hydroids). As biochemical markers, most of the cloned GFPs have specific niches (Shaner N C, Steinbach P A, Tsien R Y. A guide to choosing fluorescent proteins. Nat Methods. 2005 Dec.;2(12):905-9.). For example, as a group, they span the color range from blue to red in their fluorescence emission properties and they come as monomers, dimers, or tetramers. There are differences in photostability, pH sensitivity, extinction coefficient, and fluorescence quantum yield. Some express better than others in heterologous organisms and some seem ideally suited for certain instrument systems (for example, fluorescence activated cell sorting (FACS), confocal microscopy, argon ion laser excitation, fluorescence resonance energy transfer (FRET), and western blots). The abbreviation GFP is usually used to refer to the proteins isolated from, or cloned from, the jellyfish Aequorea victoria, or on occasion to the sea pansy or Renilla reniformis. 
To fit into a particular niche, physical and spectral properties of a given fluorescent protein (FP) can be altered by mutagenesis (selected reviews: Heim R, Tsien R Y. Engineering green fluorescent protein for improved brightness, longer wavelengths and fluorescence resonance energy transfer. Curr Biol. 1996 Feb. 1;6(2):178-82; Shaner N C, Patterson G H, Davidson M W. Advances in fluorescent protein technology. J Cell Sci. 2007 Dec. 15;120(Pt 24):4247-60.). But, the degree of alteration possible seems to be related to the starting amino acid structure of the “parent” protein. Sometimes this intrinsic sequence is called the “scaffold.” It is proposed herein that GFPs with very different inherent scaffolds could be genetically modified in ways that other GFPs (having different scaffolds) cannot be modified. Random or directed mutagenesis of a truly novel GFP has been developed herein.